Photovoltaic devices are known in which an amorphous silicon layer which is substantially intrinsic is formed between a crystalline silicon substrate and a doped amorphous silicon layer.
As means for improving output characteristics of the photovoltaic device having such a structure, a structure has been disclosed in which oxygen is introduced into an interface portion between the silicon substrate and the intrinsic amorphous silicon layer (refer to Patent document 1).
A structure has been disclosed in which an i-type amorphous silicon thin film is provided between a crystalline silicon substrate and a p-type amorphous silicon, and boron (B) are introduced into an interface between the crystalline silicon substrate and the i-type amorphous silicon thin film (refer to Patent document 2).
These structures have been known to improve interface characteristics of the crystalline silicon substrate and the amorphous silicon to thereby suppress recombination of carriers at the interface.